Audiologic studies done previously at NIH (1981) have suggested that this population has frequent auditory system anomalies. Further investigation of hearing and auditory system function is necessary in order to assess the problem and to relate it to the larger problems (cognitive and neurologic assessment) of this protocol. As of 1 May 1985, patients have only recently started to be studied audiologically, thus insufficient data precludes even preliminary interpretation. Study is ongoing and will include several measures of behavioral and electrophysiological auditory function including auditory evoked potentials.